I store my ammo in 50 cal ammo cans (mil surplus). 9mm boxes fit well in some I've found. Other calibers and shotgun shell boxes fit so so. It keeps them away from the humidity as the cans have a rubber seal.
Some of them are in the garage on a shelf; others are inside in closets.
Years back, I found some 50 cal ammo cans that are hinged on the long side and open much easier that the ones with the latch and hinge on the short sides. I havent seen any at stores since, other than 12 pallets of them from a mil surplus auction house. I wasnt sure that many would go over well here
